It has been found that a vast majority of accidents which occur at a loading dock are due to human error. The seriousness of these accidents is oftentimes increased in instances where powered material handling equipment is utilized in loading and/or unloading a truck parked at the dock. An inordinate number of these accidents are precipitated by the parked truck being improperly secured in place, or the driver of the truck inadvertently and prematurely moves the truck away from the dock before the loading dock personnel and handling equipment have cleared the truck bed.
Heretofore, in an effort to reduce this potential hazard, various devices have been employed to secure the parked truck in place such as blocks, cables, chains, and the like. These devices, however, have oftentimes proved ineffective for one or more of the following reasons: (a) the blocks became lost or stolen, (b) the blocks were ineffective where the surface of the roadway supporting the truck was slippery due to rain, snow, ice, and/or oils: (c) the cable or chain was awkward and difficult to handle; (d) unless the blocks were properly wedged in place or the cable or chain made taut, the truck had a tendency to creep away from the dock as the material handling equipment moved on and off the truck bed; and (e) the primary responsibility for properly utilizing such devices rested with the truck driver and not the dock attendant, and therefore, such driver might become preoccupied on other matters and forget to take the necessary precautionary steps to insure proper securement of his vehicle to the dock, or the driver might consider such devices or precautionary steps a nuisance and thus ignore same.
In other instances more elaborate securing devices have been proposed which are either of a costly and complex construction; require an outside source of electrical, pneumatic, and/or hydraulic power to effect operation thereof; are highly susceptible to malfunction due to changes in climatic conditions; interfere with the full use of the loading dock when powered material handling equipment is being utilized; or are incapable of interlockingly engaging the ICC bars of parked vehicles where the height of the ICC bars varies over a wide range.